Liver performs many essential functions, such as a metabolic function of treating various nutrients, a function to synthesize plasma protein, e.g., albumin, and a function of detoxifying toxins such as alcohol or drug. Also, a kidney performs functions of discharging urea nitrogen which is a metabolite of a protein, removing extra water inside a body, and regulating blood pressure. When a liver is damaged, the substances that have to be removed from a body by the hepatic metabolism, such as ammonia and bilirubin, are accumulated in the body. The accumulation causes complications such as jaundice, hepatic encephalopathy, acute kidney failure, systemic inflammation, and multiple organ failure. Similarly, when there is a kidney dysfunction, water and protein-metabolic substances which need to be removed out of the body are accumulated, causing complications such as uremia and cardiovascular disease.
In case of acute liver failure, although a liver transplant is regarded as the only cure, according to the liver transplant data published by OPTN/SRTR Annual Report in 2011, only 36% of the patients waiting for a liver transplant actually receive the treatment. Organ transplantation data from Korean Network for Organ Sharing (KONOS) also show that only 22% of the patients on the waiting list receive the liver transplant, because the number of donor liver is substantially short as compared with the number required for the liver transplant. Similarly, in the case of the kidney transplant, approximately 30% of patients with end-stage renal disease receive the kidney transplant. Thus, when the liver transplant or the kidney transplant is not performed in a timely manner, a treatment for purifying blood is required in which blood is circulated out of body and toxins are removed through various methods, such as dialysis, filtration, or adsorption.
Artificial liver apparatuses currently in clinical use are limited only to MARS of Gambro and Prometheus of FMC. Prometheus has such configuration that plasma is separated from blood to be filtered through ion-exchange resin adsorbent for removal of toxins existing in the plasma and then hemodialysis is performed after the plasma separation and adsorption. Accordingly, Prometheus apparatus ends up with a complicated system including a plasma separation filter, two adsorption filters removing toxins from plasma, and hemodialysis process, giving rise to a high treatment cost.
MARS is configured to remove hepatic toxins from blood using a dialyzer in which mass transfer occurs between blood and dialysate when blood and dialysate flow with a semi-permeable membrane therebetween as seen in a general hemodialysis apparatus. However, as MARS is compared with a general hemodialysis apparatus required for patients with renal failure, it is characterized by the use of a plasma protein called albumin which is added to the dialysate, such that hepatic toxins, various protein-bound toxins, as well as uremic toxins can be removed. Here, the albumin needs to be regenerated, which necessitates an additional hemodialyzer, activated charcoal and ion-exchange resin filters. Accordingly, due to the several stages of dialysis and adsorbent filters required for MARS treatment, as well as the expensive albumin, MARS comes to a complicated system and a costly treatment like Prometheus.